Adjustable chair



y 28, 1954 R. L. EHRKE E l'AL 3,142,509

ADJUSTABLE CHAIR Filed July 17, 1962 2 Sheets-Sheet 1 INVENTORS ROBERT L. EH RKE FLOYD E. KNECHT vw gmwk ATTORNEY July 28, 1964 R. EHRKE ETAL ADJUSTABLE CHAIR Filed July 17, 1962 2 Sheets-Sheet 2 INVENTOR. ROBERT L.EHRKE FLOYD E KNECHT BY M LMLWF ATTORNEY United States Patent f 3,142,569 ADJUSTABLE CHAIR Robert L. Ehrke, Rte. 6, 2510 Scenic Drive, and Floyd E. Knecht, 1611 Ardmore Ave, both of Modesto, Qalif. Filed July 17, 1962, Ser. No. 210,386 Claims. (Cl. 297-82) This invention relates to adjustable chairs, and more particularly to a dental or surgical chair which includes, in addition to a seat height control means, an adjustment means for simultaneously reclining the back rest, raising the leg rest, and tilting the seat and arm rests to adjust an occupants position between sitting and fully reclining.

Even though the ensuing description place-s particular emphasis on the use of the adjustable chair of this invention for the seating of dental patients, it is to be understood that this invention is equally applicable to the seating of medical and surgical patients for treatment and surgery. Further, the adjustable chair of this invention may also be advantageously employed outside the medical, dental and surgical field, either for general purposes where an occupant controls the adjustments himself or for special purposes such as wheel chairs or the like, as will become more apparent from the ensuing description. In many of the latter applications, the seat height adjustment that is the vertical control, may be dispensed with.

Dental chairs are used in dental offices to place patients in a position to permit the attending dentist to perform a Variety of different tasks incident to dental treatments and operations. One of the desirable features of a dental chair is its adjustability to comfortably and quickly accommodate patients in different inclined positions for different kinds of treatment or surgery. Also, a dentists chair should permit a general vertical adjustment to enable dentists of different heights or working habits, in the treatment of patients of different heights, to give treatments in comfort and without undue strain. All dentists chairs heretofore known have been found wanting in the range, type and speed of their adjustment features in one or more respects.

It is therefore a primary object of this invention to provide an adjustable chair enabling an operator to change the position of inclination of an occupant.

It is a further object of this invention to provide an adjustable chair giving an operator, such as a dentist, doctor or surgeon, an opportunity to change the position of a patient-occupant easily and quickly to any degree of inclination so that the patients back moves down and legs move up together with proper inclination changes of the seat and arm rests.

It is another object of this invention to provide an adjustable chair in which the change of inclination of one portion of the chair produces a predetermined change of inclination of all other portions of that chair.

It is still another object of this invention to provide an adjustable chair in which a change of inclination of one frame member produces a change of inclination of all other frame members in such a manner that a comfortable transition from a sitting to a reclining position is provided for the occupant.

Other objects and a better understanding of the invention may be had by reference to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of the adjustable chair of this invention, the chair being shown adjusted in its seat ing position;

FIG. 2 is a side veiw of the adjustable chair of this invention, the chair being shown adjusted in its reclining position; and

FIG. 3 is an enlarged perspective view, partially frag- 3,142,509. Patented July 28, 1964 mentary, of the left side of the chair of FIG. 1 showing details of the arm rest member and the adjustment means.

Referring now to the drawings, in which like characters designate like parts, adjustable chair 11) includes a base 11 for supporting a main frame 12 above the floor or a support platform. Base 11 may include a vertical adjustment means such as a hydraulically actuated piston or post 13 to which main frame 12 is secured. Actuation of the vertical adjustment means may be accomplished by means of a foot operated switch 14 at the lower portion of base 11. Base 11, together with piston 13 and its actuating mechanism, may take the form of a conventional hydraulically operated center post chair support. As is well known to those skilled in the art, instead of utilizing a hydraulically operable post, an electric actuating mechanism, such as one utilizing a driven lead screw and a worm and pinion arrangement, may be utilized.

Main frame 12 may be provided with a pair of spaced, vertically extending side walls 15, 16. A back rest frame 17, which may be formed of aluminum tubing 18 bent into a substantially U-shaped frame, has a pair of cross members 19 rigidly aflixed thereto to provide rigidity to tubing 18. Furthermore, back rest frame 17 is shaped generally to accommodate a back rest pillow (not shown) mounted either directly or by way of a pillow backing board to cross members 19 or tubing 18 or both.

There is further provided a seat frame 20 which may comprise two tubular side members 21, 22 having crimped end portions which are held in fixed spaced relationship by three cross members 23 rigidly aflixed to side members 21 and 22. Cross members 23 preferably have a flat upper surface to support a seat pillow (not shown) having a suitable pillow backing plate. The lower end portion of back rest frame 17 and the rear end portion of seat frame 20 are hingedly connected to one another and to the rear of main frame 12. In practice it has been found convenient to utilize a pair of pivot pins 24 journalled in bearings suitably accommodated in the rear end portions of seat frame 2@ and lower end portions of back rest frame 17. Pivot pins are supported respectively by side walls 15 and 16. Of course, instead of using a pair of individual pivot pins 24, a single rod extending across main frame 12 may be utilized.

A leg rest frame 31) may likewise be formed of a tubular member 31 bent into U-shape. Cross members 32 are fastened to opposite sides of tubular member 31 for rigidity of construction and for receiving a leg rest pillow (not shown) which may be fastened to cross members 32 or tubular member 31 or both. The crimped forward end portions of seat frame 20 are hinged or pivotally mounted, by means of pivot pins 33, to a portion of leg rest frame 30 which is a predetermined distance below its upper end portion.

A pair of arm rest members 40 and 41 are provided to tie back rest frame 17 to leg rest frame 30 and to support arm rest pillows (not shown) upon their respective flat upper sides. More particularly, arm rest members 40 and 41 each comprise a substantially horizontal portion which may be formed of square or rectangular tubing 42 whose forward end portions may be closed as shown at 43. The rear end of tubular member 42 maybe left open to provide an opening for inserting hearing or guide means 44 into their respective inner channels 51. After hearing means 44 are inserted, the rear opening may likewise be closed. m

Side plates 15 and 16 maybe provided With a vertically extending portion 45 carrying a bearing support member 46 rigidly affixed thereto. The upper extremity of each bearing support member 46 is provided with a horizontal opening for a shaft or bolt 47. A pair of bearings 48 are secured, by means of shaft 47, to opposite sides of bearing support members 46.

Bearings 48 may be cylindrical disc or roller or ball bearings having an outer diameter dimensioned for sliding reception by the substantially rectangular bearing channel 51 inside member 41 and 42. In operation, the outer surface in case of disc bearings or the race in case of a roller or ball bearings, may engage either top surface 49 or bottom surface 50 of bearing channel 51. When a load is placed upon seat frame 20, bearings 48 support this weight.

An elongated slot 52 is provided in lower wall 50 of bearing channel 51 to clear bearing support member 46 as the arm rest members move. In this manner arm rest members 40 and 41 may slide forward and backward and may tilt to any desired angle about the axis of shaft 47. In other words, arm rest members 40 and 41 are slidingly and pivotally guided by bearings 48.

The rear end portion of arm rest members 40 and 41 are pivotally connected, by means of pivot pins 53, to back rest frame 17 at a selected distance from a vertical height above pivot pin 24. The exact height of pivot pins 53 is chosen such that a person seated in the chair of this invention in the upright or inclined position finds his elbows resting upon arm rest members 40 and 41 at a convenient height.

The front end portion of arm rest members 40 and 41 have rigidly connected thereto short tubular members 55 of selected length which pivotally engage the end portions of tubular member 31 of leg rest frame 30 by means of pivot pins 56. As a practical matter, short members 55 may be provided with an car 57 and the end portion of member 31 with a Ushaped cutout 58 for engaging ear 57 to form a pivot joint.

It is important to realize that, as chair is tilted all the way back, the length of short tubular members 55 determines the height of the front portion of arm rest members 40 and 41 as is best shown in FIG. 2. Accordingly, the length of members 55 is selected so that in the reclined position, the forward portion of arm rest members 40 and 41 are at a height which assures comfortable support to an occupant seated in chair 10. On the other hand, if chair 10 is in its seating or erect position, that is, leg rest frame is in a substantially vertical position, the end portions of leg rest frame 30 above pivot pin 33 are axially aligned with members 55 and thereby determine the height of the front portion of arm rest members and 41. Accordingly, the distance between pivot pins 33 and 56 is selected such that the front of arm rest frames 40 and 41 are at a proper position when the chair is in its erect position.

Connected between main frame 12 and leg rest frame 30 is an actuating mechanism 59 for changing the inclination of chair 10 to suit. More particularly, a U- shape bracket or yoke member 61 is aifixed to the lower surface of main frame 12 and a similar bracket 61 is afiixed to leg rest frame 30. A pivot bracket 62 is pivotally mounted about pivot pin 63 in bracket 61 and carries a shaft 64. Shaft 64 is connected to housing 65 which houses an electric motor and a gearing connection to a threaded spindle 66. The gearing connection may comprise a worm mounted to the motor shaft and engaging a worm gear mounted to spindle 66. A threaded collar 67 is pivotally supported in bracket 60 by pivot pin 68 and engages threaded spindle 66.

In operation of adjustable chair 10, application of electric power to the motor of actuator means 59 causes rotation of threaded spindle 66 connected to the motor. As threaded spindle 66 rotates, and depending on the direction of rotation, threaded sleeve 67 either clockwise or anticlockwise rotates leg rest member 30 via cross member 32 about pivot pins 33.

Since cross member 32 is rigid with leg rest frame 30 and pivotally mounted about pin 33 to seat frame 20 which in turn is pivotally mounted to side walls 15 and 16 of main frame 12, this motion causes a change in the at m 0f Cha As is easily seen, the various 4 frame members, due to their interconnection have a rule of action determined by the distances between the various pivot points.

More particularly, adjustable chair 10 is provided with three pivot points 24, 53 and 47 which provide the basic stabilization and two further pivot pins 33 and 56 which follow the change of position of the various members. As chair 10 is moved from its erect to its inclined position in response to rotation of lead screw 66, leg rest frame 30 is rotated clockwise about pivot pins 33. Rotation of leg rest frame 30 causes a raising of pivot points 33 and 56 thereby clockwise rotating seat frame 20 about pivot point 24 and clockwise rotating arm rests 40 and 41 about pivot point 47. Arm rests 40 and 41 are also laterally displaced thereby rotating back rest frame 17 about pivot points 24.

In practice a person is usually seated when chair 10 of this invention is in erect position and thereafter the desired degree of inclination is provided by actuating the motor of actuating means 60 and the desired vertical height is provided by actuating hydraulic post 13. It is to be understood that other actuating means, such as for example hydraulic or pneumatic fluids may be utilized in connection with actuating means 60, suitable modifications being made by replacing threaded spindle 66 and motor housing with a hydraulically or pneumatically operated ram.

There has been described an adjustable chair for changing the inclination of the back rest, the leg rest, the seat, and the arm supports, by means of an actuating means. The relative changes of inclination of the various parts are dependent upon the distances between the various pivot points and a careful selection of the position of the various pivot points results in a selected mode of operation of the various portions of the chair. The chair of this invention is combined with an adjustable mount permitting a change of the vertical height of the chair.

What is claimed is:

1. A dentist chair comprising: a base including a hydraulically operable and vertically adjustable base member; a main frame including a pair of spaced side plates mounted upon said base member; aligned pivot pin means carried by said spaced side plates; a seat frame extending between said side plates having one of its end portions pivotally journalled about said pivot pin means; a back rest frame extending between said side plates having one of its end portions pivotally journalled about said pivot pin means; a leg rest frame extending between said side plates pivotally journalled, at a point located a selected distance from one of its end portions, to the other end portion of said seat frame; bearing means carried by each of said spaced side plates in substantial axial alignment with one another; an arm rest member for each side plate, each arm rest member including an elongated bearing channel dimensioned for sliding reception of said bearing means and an elongated slot in one of the sides of said bearing channel dimensioned for reception of said side plate, one end of said arm rest member being pivotally journalled to said back rest frame at a selected distance from said pivot pin means, the other end of said arm rest member including an extension member of selected length extending substantially perpendicular to the direction of extension of said bearing channel, the end of said extension member being pivotally journalled to the end portion of said leg rest frame which is said selected distance from its pivot point with said seat frame; a motor driven threaded spindle pivotally mounted to the underside of and between the other end portion of said leg rest frame and the pivot point of said leg rest frame with said seat frame; and a threaded engagement means for engaging said motor driven spindle, said engagement means being pivotally journalled to said main frame.

2. A dentist chair in accordance with claim 1 in which said bearing channel is substantially rectangular and in which said bearings means comprise a pair of coaxially positioned antifriction bearings straddling said side plates for engagement with the upper and lower side walls of said bearing channel and wherein said slot is in said lower side wall.

3. An adjustable chair comprising: a main frame; a back rest member; a seat member, said back rest member and said seat member being pivotally journalled with respect to one another and said main frame; a leg rest member pivotally joumalled, mediate its ends points, to said seat member to define respectively a first and a second end portion on opposite sides of the pivot connection; a pair of arm rest members respectively disposed on opposite sides of said main frame, each arm rest member being pivotally journalled, at opposite end portions re spectively, to said back rest member and a point on said first end portion which is spaced from the pivot connection between said leg rest member and said seat member, said arm rest member further being slidingly and pivotally journalled to said main frame; and axially extensible leg rest actuating means connected between said main frame and a point on said second end portion which is spaced from the pivot connection between said leg rest member and said seat member.

4. An adjustable chair in accordance with claim 3 in which said axially extensible leg rest actuating means comprises a threaded spindle, a threaded collar engaging said threaded spindle and motor means for imparting relative rotation between said threaded spindle and said threaded collar.

5. An adjustable chair in accordance with claim 3 in which said main frame includes a vertically adjustable base member and in which said axially extensible leg rest actuating means includes a motor driven spindle and a threaded collar engaging said motor driven spindle, said motor driven spindle and said threaded collar being respectively pivotally journalled to said main frame and said leg rest member.

References Cited in the file of this patent UNITED STATES PATENTS 1,437,920 Stephens Dec. 5, 1922 1,721,027 Meyer July 16, 1929 2,130,754 Cornell et al Sept. 20, 1938 2,655,200 Lorenz Oct. 13, 1953 2,655,201 Lorenz Oct. 13, 1953 2,714,922 McKibbon et a1 Aug. 9, 1955 2,913,738 Wise Nov. 24, 1959 3,016,264 Hughes Jan. 9, 1962 FOREIGN PATENTS 506,214 Italy Dec. 21, 1954 

1. A DENTIST CHAIR COMPRISING: A BASE INCLUDING A HYDRAULICALLY OPERABLE AND VERTICALLY ADJUSTABLE BASE MEMBER; A MAIN FRAME INCLUDING A PAIR OF SPACED SIDE PLATES MOUNTED UPON SAID BASE MEMBER; ALIGNED PIVOT PIN MEANS CARRIED BY SAID SPACED SIDE PLATES; A SEAT FRAME EXTENDING BETWEEN SAID SIDE PLATES HAVING ONE OF ITS END PORTIONS PIVOTALLY JOURNALLED ABOUT SAID PIVOT PIN MEANS; A BACK REST FRAME EXTENDING BETWEEN SAID SIDE PLATES HAVING ONE OF ITS END PORTIONS PIVOTALLY JOURNALLED ABOUT SAID PIVOT PIN MEANS; A LEG REST FRAME EXTENDING BETWEEN SAID SIDE PLATES PIVOTALLY JOURNALLED, AT A POINT LOCATED A SELECTED DISTANCE FROM ONE OF ITS END PORTIONS, TO THE OTHER END PORTION OF SAID SEAT FRAME; BEARING MEANS CARRIED BY EACH OF SAID SPACED SIDE PLATE IN SUBSTANTIAL AXIAL ALIGNMENT WITH ONE ANOTHER; AN ARM REST MEMBER FOR EACH SIDE PLATE, EACH ARM REST MEMBER INCLUDING AN ELONGATED BEARING CHANNEL DIMENSIONED FOR SLIDING RECEPTION OF SAID BEARING MEANS AND AN ELONGATED SLOT IN ONE OF THE SIDES OF SAID BEARING CHANNEL DIMENSIONED FOR RECEPTION OF SAID SIDE PLATE, ONE END OF SAID ARM REST MEMBER BEING PIVOTALLY JOURNALLED TO SAID BACK REST FRAME AT A SELECTED DISTANCE FROM SAID PIVOT PIN MEANS, THE OTHER END OF SAID ARM REST MEMBER INCLUDING AN EXTENSION MEMBER OF SELECTED LENGTH EXTENDING SUBSTANTIALLY PERPENDICULAR TO THE DIRECTION OF EXTENSION OF SAID BEARING CHANNE, THE END OF SAID EXTENSION MEMBER BEING PIVOTALLY JOURNALLED TO THE END PORTION OF SAID LEG REST FRAME WHICH IS SAID SELECTED DISTANCE FROM ITS PIVOT POINT WITH SAID SEAT FRAME; A MOTOR DRIVEN THREADED SPINDLE PIVOTALLY MOUNTED TO THE UNDERSIDE OF AND BETWEEN THE OTHER END PORTION OF SAID LEG REST FRAME AND THE PIVOT POINT OF SAID LEG REST FRAME WITH SAID SEAT FRAME; AND A THREADED ENGAGEMENT MEANS FOR ENGAGING SAID MOTOR DRIVEN SPINDLE, SAID ENGAGEMENT MEANS BEING PIVOTALLY JOURNALLED TO SAID MAIN FRAME. 